U.S. Pat. No. 3,737,003, issued June 5, 1973 to Duane E. Beals and Russell D. Page illustrates a prior art control linkage.
In vehicles such as lift trucks, a serious problem exists in getting full access to the tops of the compartments which hold the batteries or engines which power the trucks for installation, servicing and like purposes. The driver's seat generally sits upon the hood of such a compartment and controls should be as near thereto as possible for easy access and maximum driver control. Generally, a rather large and very heavy battery box fits in a battery compartment and a large engine within an engine compartment. Battery boxes must generally be lowered into the battery compartment, and engines into the engine compartment, from above. This, in turn, requires that the top or hood of the compartments be removable. Prior art battery compartments, for example, have generally had the tops or hoods thereof detachable by release of bolts, hooks, latches or the like. Thus, these battery compartments have normally been multi-piece to allow disassembly into separate parts or pieces. Such assembly and disassembly has, of course, been time consuming, thus increasing down-time of the vehicles.
As an alternative, the hood of the battery compartment can be made integral with a front panel and the front panel can be pivoted near the floor of the vehicle whereby the hood and front panel can be pivoted upwardly and forwardly away from the battery compartment thus allowing full access to the top thereof. In such an arrangement the operator seat is generally atop the hood. However, when such an arrangement is used it has normally been necessary to position the control levers and, more particularly, the linkages which control movement of the control valve stem, far forwardly on the truck, generally quite significantly removed from comfortable operator manipulation thereof to allow the aforementioned pivoting. This has led to operator fatigue and somewhat reduced control of the vehicle.
It is desirable to have the control linkage adjacent the operator so that the operator can have delicate control of the vehicle and, yet, to have a pivotal hood-front panel arrangement whereby it is not necessary to make use of bolts, hooks, latches and the like to assemble and disassemble separate pieces which, when assembled, constitute the battery or engine compartment of the vehicle. Prior to the present invention, such a versatile control valve linkage was not available in the relevant art. It would also be desirable if the arrangement of such a linkage would allow the control valve itself to be placed beneath the floor panel of a vehicle whereby it would be fully protected from any possible damage. A further advantage results when the valve is not shifted from its original setting upon rotation of the control linkage during raising of the hood whereby operator readjustment is not required.